Conservative Republicans warn that the administration is determined to expand its regulatory reach and curb the extrac­tion of valuable energy resources, while many Democrats and their environmentalist allies argue that the policy will keep the ocean healthy and reduce conflicts over its use.

The wrangling threatens to overshadow a fundamental ­issue: the country’s patchwork approach to managing offshore waters. Twenty-seven federal agencies, representing interests as diverse as farmers and shippers, have some role in governing the oceans.

Obama’s July 2010 executive order set up a National Ocean Council, based at the White House and designed to reconcile competing interests of agencies and ocean users.

The policy is having an ­impact. The council is trying to broker compromise among six federal agencies over the fate of defunct offshore oil rigs in the Gulf of Mexico. Recreational fishermen want the rigs, which attract fish, to stay, but some operators of commercial fishing trawlers consider them a hazard and want them removed.

Still, activists are having little success when invoking the ocean policy to press for federal limits on traditional maritime interests. The Center for Biological Diversity cited the policy as reason to slow vessels traveling through ­marine sanctuaries off California. Federal officials ­denied the petition.

During a House Natural ­Resources Committee hearing on ocean policy last year, the panel’s top Democrat, Representative Edward J. Markey, Democrat of Malden, said, ‘‘Oppos­ing ocean planning is like opposing air traffic control.”

Representative Steve Southerland, Republican of Florida, who is in a tight reelection race, retorted that the policy was ‘‘like air traffic control helping coordinate an air invasion on our freedoms.’’ An environ­mental group called Ocean Champions is spending hundreds of thousands of dollars to unseat him.

Taryn Tuss, spokeswoman for the White House Council for Environmental Quality, said the policy does not give the federal government new authority or change congressional mandates.

‘‘It simply streamlines implementation of the more than 100 laws and regulations that already affect our oceans,’’ she said.

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